LETTERS A Plea for the Cubic Centimeter To the Editor: I should like to make a plea to return to a general use of the term cubic centimeter instead of the tongue twisting and confusing milliliter. The cubic centimeter was used originally to denote the volume of water, at its supposed maximum density of 4 O centigrade, of a cube exactly one centimeter on 1 edge. I t was found afterward the maximum density of water is at 3.9S°C. The liter is defined by theInternationalCommission of Weights and Measures as the volume occupied by the mass of one kiogram of pure water at its maximum deusity and under normal atmospheric pressure. The milliliter is defined as one-thonsandth of a liter. Thus the milliliter has a volume 0.0003 larger than a cubic centimeter. More exact values from different sources give the milliliter as having a volume 0.000027, 0.000028, and 0.000029 greater than the cubic centimeter. The difference is so slight it cannot be
determined by ordinary means of measuring volumes. Burets and other means of measuring volumes very rarely are measured more accurately than two decimal places in terms of cubic centimeters or milliliters. Cubic centimeter can be pronounced more quickly and with less use of the tongue than the term, milliliter. I t must be admitted cc. can be written more quickly and easily th& ml. I t has been found frequently that beginning students confuse the termsmilliliterand millimeter. Sometimes calculations are made wherein milliliters are converted into cubic millimeters. This adds to the confusion of students in interpreting the terms. A good deal of confusion is avoided by using cubic centimeter instead of milliliter. The other terns (cubic meter, cubic decimeter, and cubic millimeter) use "cnbic" in connection with the unit of length, to denote volumes. Since the difference between the units is so small as not to be capable of measurement by usual means, why should an exception be made in the use of the term most often used by scientists for denoting
volumes? Why should not chemists and other scientists use the term that can be pronounced and written more easily and quickly? V. T. JACKSON UNIVERSITY OP FLORIDA GAINESVILLE, FLORIDA
Doing a Job? Yes!>
T o the Editor: I have just had a little experience on a problem that involves all kinds of chemistry teachers. Since I am fairly new a t this game of high-school chemistry teaching, my knowledge of the stand that the American Chemical Society and our journals have taken on this situation is not very great. But I feel, as I am sure those others who have had similar experiences, that there should he some definite attempt to remedy the situation. About six weeks ago a student who works in a local fillimg station brought in a sample of a new type ''permanent" antifreeze. His boss had begun to wonder about it for the stuff had crystallized in the jugs. I had some experience with calcium chloride antifreezes six or seven years ago while working in the research department of Commercial Solvents Corporation. So I felt this was one of the same type that has appeared several times during the past twenty years. Tests soon revealed that my idea was correct. Knowing the corrosion difficulties encountered with this material in automotive systems I suggested that we m u some simple corrosion tests as a class project, and we found that it was particularly corrosive on aluminum and copper. We then tried to estimate the cost of this particular preparation and considered it a t some length. Then the students in other classes asked about this and it was called to their attention. I was very pleased with the interest in this problem until I received a call from one of the men who was selling this material. He really raked me over the coals, and some more for stating that this stuff that he was selling was no good and that it was not worth $2.65 a gallon. I went to his place of business and showed him the 1 See also page 133.
reasons for my statements and also made arrangements to let him see some actual tests that had been made on his product. Of course he was not convinced because he bought about $5000 worth of the stuff and was worrying considerably about that. Now he is stiil wondering, and so are some of the other dealers of this antifreeze in Terre Haute for a variety of difficulties are facing them. The thimg I wonder about is why there is not more publicity given to such frauds? Perhaps it is the duty of the teachers to warn against such harmful materials, to try and help the poor public so that they will not be such suckers. If so, it is a mighty big job. Should a few of us continue to stick our necks out and condemn such practices, or should we just become cynical and avoid such situations as these? Since this experience I find that there are about six other calcium chloride antifreezes on the market. A communication from the automotive section of the Bureau of Standards informs me of the correctness of our diagnosis of this situation. Still, unless one knew, he might he a victim very easily. Also I have learned, and so far kept rather quiet, about these tire preservatives that are so common now. Some of them are sodium silicate which on drying becomes abrasive. Am I doing my job? WILLIAMG.&SSEL WILEYHIOHSCHOOL INDIANA T E ~HAUTE, E Tetryl T o the Editor: Permit me to point out an error in "A Brief Coume in Chemistry and Warfare," by S. J. French in the January issue, page 34 . . "tetryl (tetranitroanilme)." Tetranitroaniline has been used for military purposes, but has been found too unstable; i . e., in seven or eight years' normal storage, it has been known to explode spontaneously. "Tetryl" (trinitr~phenylmeth~].]. nitrarnine) is sometimes erroneously called "tetranitroi methyl aniline," hut never "tetranitroanilme." A.T.BURTSELL COLLEGE oa THE CITYon NEWYORK NEWYORK, NEWYORK
.
